The control of undesirable grasses is important in the cultivation of many important broadleaf agricultural species such as soybeans, peanuts and cotton, as well as in the cultivation of many horticultural species. Moreover, the presence of such weeds on noncropped areas may present a fire hazard, or may result in the undesirable drifting of sand or snow or irritation to persons with allergies. Accordingly, it would be beneficial to control the growth of undesirable grasses, particularly in a manner which would allow for the selective control of such plants without concurrent injury to desirable broadleaf crops or vegetation.
Among the classes of compounds which have been employed in the past to control the growth of undesirable vegetation are certain quinoxalinyloxyphenoxy compounds. Thus, Ura et al in U.S. Pat. No. 4,629,493 disclose certain quinoxalinyl compounds, including 6-membered homocyclic ring derivatives such as benzyl 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]-propanoate, which are useful as selective herbicides. Similarly, in European Patent Application 46,467, Ura et al show a number of quinoxalinyloxyphenoxy compounds, including a morpholino ester thereof, which are useful as herbicides.
Somewhat similarly, U.S. Pat. No. 4,429,167 to Lee discloses a broad range of 3-alkoxy-4-substituted-phenoxy-2,-3-unsaturated acids, including quinoxalinyl derivatives thereof which are selective herbicides for grasses, while U.S. Pat. No. 4,609,396 to Fawzi shows a variety of quinoxalinyloxy ethers which are useful for controlling grass weeds in broadleaf plants. Chemical Abstracts 98, 198278m (1983) discloses herbicidal glycidyl quinoxalin-2-yloxyphenoxypropionates while European Patent Application 206,772 shows quinoxalinyloxybenzyl ester compounds which are useful for the selective control of weeds in rice. Spanish Patent Application 8,603,431 shows herbicidal alkyl quinoxalinyloxyphenoxypropanoates while European Patent Application 113,831 shows selective herbicides which are carbamylethyl esters of quinoxalinyloxyphenoxypropanoic acids. European Patent Application 121,871 shows herbicidal phosphoric acid esters of quinoxalinyloxyphenoxypropanoates while U.S. Pat. No. 4,499,271 shows phosphoric acid esters of quinoxalinyloxyphenoxypropanoates. German Application 3,433,390 shows silane esters of quinoxalinyloxyphenoxypropanoic acid, while Kruger et al in U.S. Pat. No. 4,601,748 disclose herbicidal 2-phenoxypropionic acid derivatives of pentitols.
In contrast, U.S. Pat. No. 4,564,381 to Bieringer et al shows a very broad class of compounds, including many quinoxalinyloxyphenoxypropanoic esters which function as plant growth stimulants.
While many of the compounds shown in the above publications exhibit desirable herbicidal activity, it would nevertheless be desirable to possess herbicides which exhibited enhanced selective control of undesirable grasses.
Accordingly, it is an object of this invention to provide a class of novel compounds which exhibit unexpectedly desirable selective herbicidal activity.
It is a further object of this invention to provide a method of controlling undesirable weeds.
These objects and other additional objects will become more fully apparent from the following disclosure and accompanying examples.